The outcomes of Re-Redo bariatric surgery—results from multicenter Polish Revision Obesity Surgery Study (PROSS)

The increasing prevalence of bariatric surgery has resulted in a rise in the number of redo procedures as well. While redo bariatric surgery has demonstrated its effectiveness, there is still a subset of patients who may not derive any benefits from it. This poses a significant challenge for bariatric surgeons, especially when there is a lack of clear guidelines. The primary objective of this study is to evaluate the outcomes of patients who underwent Re-Redo bariatric surgery. We conducted a retrospective cohort study on a group of 799 patients who underwent redo bariatric surgery between 2010 and 2020. Among these patients, 20 individuals underwent a second elective redo bariatric surgery (Re-Redo) because of weight regain (15 patients) or insufficient weight loss, i.e. < 50% EWL (5 patients). Mean BMI before Re-Redo surgery was 38.8 ± 4.9 kg/m2. Mean age was 44.4 ± 11.5 years old. The mean %TWL before and after Re-Redo was 17.4 ± 12.4% and %EBMIL was 51.6 ± 35.9%. 13/20 patients (65%) achieved > 50% EWL. The mean final %TWL was 34.2 ± 11.1% and final %EBMIL was 72.1 ± 20.8%. The mean BMI after treatment was 31.9 ± 5.3 kg/m2. Complications occurred in 3 of 20 patients (15%), with no reported mortality or need for another surgical intervention. The mean follow-up after Re-Redo was 35.3 months. Although Re-Redo bariatric surgery is an effective treatment for obesity, it carries a significant risk of complications.


Ethics statement
All procedures have been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.Informed consent for surgical treatment was obtained from all patients before surgery.Protocol has been registered at clinical trials.gov(NCT05108532).There were no changes in treatment for patients included due to the study.The course of the study was closely monitored by a primary investigator who processed and verified any missing or unclear data submitted to the central database.The study was approved by the Bioethics Committee of the Regional Chamber of Physicians, District of Warmia and Mazury, Poland (23/2021/VIII).

Complications
Complications after Re-Redo surgery occurred in 3 of 20 patients (15%).None of them required further surgical intervention.Among these complications were: 1. Vomiting more than once a week-a patient who had SG as PBS, reSG as Redo because of weight regain and OAGB as Re-Redo because of insufficient weight loss (< 50%EWL).2. Esophagitis and nutritional deficiencies-a patient who had AGB as PBS, band removal with simultaneous SG as Redo because of gastric band intolerance (nausea, pain after eating) and RYGB as Re-Redo because of weight regain and also GERD. 3. Persistent abdominal pain complaints, episode of biliary colic, GERD-a patient who had AGB as PBS, gastric band removal as Redo because of band dysfunction along with GERD-associated symptoms and SG as Re-Redo because of weight regain.

Discussion
Some patients undergo multiple bariatric operations in their lifetime.In this study we showed that Re-Redo bariatric surgery yields good results in terms of weight loss, but it might be associated with a higher risk of complications.
Bariatric surgery is a well-established obesity treating method yielding excellent outcomes, but approximately 15-20% of patients ultimately do not achieve or sustain satisfactory weight loss 15 .In addition, some patients  www.nature.com/scientificreports/may experience side effects of their bariatric surgery, such as GERD, which in some cases require surgical correction [16][17][18] .RBS is a treatment option for those who do not achieve sufficient weight loss after their primary bariatric procedure, but it is more challenging and associated with a higher risk of complications than primary bariatric surgery PBS.Consequently, it seems appropriate for RBS to be performed at centers experienced in these types of procedures [19][20][21] .
Evidence-based publications, such as meta-analysis and systematic reviews by Brethauer et al. 22 , Koh et al. 3 , and Kermansaravi et al. 23 , do support the efficacy of RBS.A trial by Sudan et al. on over 28,000 patients demonstrated RBS to be safe, with 1.9% of severe adverse events and 0.24% mortality at 1 year for corrective operations, and respectively 3.61% and 0.31% in regards to conversions procedures 24 .Studies by multicenter Polish Revision Obesity Surgery Study (PROSS) also support these arguments 14,25 .
The literature on efficacy and safety of Re-Redo bariatric surgery is sparse and based on small groups of patients.We found four studies on this subject, with the number of analyzed patients ranging from 12 to 42, mean %EWL from 43.3 to 54.4% and complication rate from 14.7 to 35.7% [26][27][28][29] .
Paper by Daigle et al. on 12 patients found mean BMI after Re-Redo surgery to be 39.9 ± 20.8 kg/m 2 and mean %EWL 54.4 ± 44.0%. 5 early complications occurred in 4 patients (33.3%), from which 2 needed operative intervention: partial gastrectomy of a necrotic gastric remnant after RYGB and mesh explantation after Roux limb lengthening with complex hernia repair.Other complications were wound infections 26 .
In study by Lunel et al. on 34 patients, final BMI was 36.8 ± 8.0 kg/m 2 and %EWL after Re-Redo surgery was 47.9 ± 32.1%.Three patients (8.8%) presented severe complication, from which two of them was diagnosed with a leak of duodenoileal anastomosis after BPD-DS, and one had heavy malnutrition after reSG and required a jejunostomy.Another two patients (5.9%) experienced minor complications, one each of pneumonia and wound abscess 27 .
Study by Raglione et al. on 30 patients showed %EWL of 53.4% and %TWL of 29.6%.The complication rate was 30%. 3 patients were recognized with early postoperative leakage; treated endoscopically or with CT scanguided drainage.2 patients had postoperative bleeding that needed blood transfusion.2 patients experienced dumping syndrome managed with dietary changes and acarbose.2 patients developed late gastrojejunostomy stricture after RYGB treated successfully with endoscopic dilatations.None of these complications required another surgical intervention 28 .
Work by Nevo et al. evaluated 42 patients that underwent RYGB as a third or subsequent bariatric surgery.From this group, 32 patients had RYGB as their Re-Redo surgery.Mean final BMI reached 34.5 kg/m 2 reflecting an excess BMI loss (%EBMIL) of 43.3%.Complication rate was 35.7%, but majority of it (10/15) were minor (Clavien-Dindo II). 5 patients needed reoperation, although 2 of these were negative explorations in suspected leak.Other reasons for reoperations included jejunojejunostomy stricture, small bowel obstruction due to adhesions, and anastomotic intraluminal bleeding 29 .
In our study, based on weight measured before and after Re-Redo, the mean %TWL was 17.4% and %EBMIL was 51.6%.13/20 patients (65%) achieved > 50% EWL.Final %TWL was 34.2 ± 11.1%.Final BMI was 31.9 ± 5.3 kg/m 2 .Mean final %EBMIL at the end of treatment was 72.1 ± 20.9%.Complications occurred in 3 of 20 patients (15%), one each of the following: vomiting more than once a week, esophagitis and nutritional deficiencies, abdominal pain complaints with episode of bilary colic, and GERD.Each of these complications were treated successfully with dietary intervention and pharmacotherapy.None of them required additional surgical intervention.There was no mortality within 30 days of Re-Redo.In terms of weight loss effectiveness and the frequency of complications, the results of our study agree with the results of the studies mentioned above.
This study has several limitations.Our results are not confronted with any other different therapeutic options, in particular those regarding non-surgical treatment.This is a non-randomized study, however, it can be extremely difficult to perform a randomized trial here.The study covered a small group of patients, but this is mainly due to the fact that such patients are rare, although their number will most likely increase over time.There is no standardization of the surgeries performed on the patients included in the study.Patients were operated by different surgeons from 12 bariatric centers.However, RBS are often performed in different surgical centers by different surgical teams and tailored individually to a patient.For this reason and due to the lack of generally accepted guidelines for RBS, full standardization may be difficult to achieve.

Conclusion
Re-Redo bariatric surgery is an effective treatment that should be considered in patients with weight regain or unsatisfactory weight loss after previous bariatric surgeries, but it comes with a considerable risk of complications.It's important to evaluate each patient on a case-by-case basis and not deny them assistance solely based on their previous bariatric treatment.Referral centers should be the optimal choice for performing RBS due to its higher complexity and the potential for complications.
Despite its potential benefits, there's still limited clinical evidence on Re-Redo bariatric surgery.Initial data appears promising, but more research is needed to gain a better understanding of its effectiveness and possible risks.

Figure 1 .
Figure 1.Flowchart of patients included in the study.

Table 1 .
General characteristics.BMI body mass index, PBS primary bariatric surgery, COPD chronic obstructive pulmonary disease, OBS obstructive sleep apnea.